Clean up the rest of the perl@ Makefiles a bit.
- Remove dependencies on modules distributed as part of perl core
- Remove references to FreeBSD < 8 and perl < 5.16
- Ensure that DOCS and EXAMPLES options exist for ports installing
PORTDOCS or PORTEXAMPLES
- Reduce unnecessary inclusions of bsd.port.options.mk by using
OPTIONS helpers and the like
- Fix some cases where dependencies were only assigned to BUILD_DEPENDS
- Fix a few of the cases where dependencies were only assigned to RUN_DEPENDS.
This one happens in many, many ports. I only applied it in cases where
it interfered with 'make test' but it should maybe be done more generally.
- Mute ${MKDIR} in installation
- Parethesize compound commands
- In www/p5-URI-Fetch, remove the ZLIB option that wasn't used

Change the way Perl modules are installed, update the default Perl to 5.18.
Before, we had:
site_perl : lib/perl5/site_perl/5.18
site_perl/perl_arch : lib/perl5/site_perl/5.18/mach
perl_man3 : lib/perl5/5.18/man/man3
Now we have:
site_perl : lib/perl5/site_perl
site_arch : lib/perl5/site_perl/mach/5.18
perl_man3 : lib/perl5/site_perl/man/man3
Modules without any .so will be installed at the same place regardless of the

At the moment 1385 ports use BUILD_DEPENDS= ${RUN_DEPENDS} and 450
ports use BUILD_DEPENDS:= ${RUN_DEPENDS}. This patch fixes ports that are
currently broken. This is a temporary measure until we organically stop using
:= or someone(s) spend a lot of time changing all the ports over.
Explicit duplication > := > = and this just moves ports one step to the left
Approved by: portmgr